A friend of mine is heading there next month with her XT fone but can't seem to find out from anyone  will it roam.

This is an email she got back from the motel she is staying at

"With the mobile phones you will have to buy a Norfolk Island sim card when you arrive from Norfolk Telecom and I think they are $25 for a tourist starter pack as we have our own network here and your phone also needs to be unlocked to put another sim card in it."

No one in Telecom in NZ or Telstra Ozz  new.  In fact most of the people at Telstra she asked last week had no idea where Norfolk Island was..